I occasionally use some staple vegetarian foods while cooking (such as tofu), but I was always amazed with these processed vegetarian alternatives to meat products just how unhealthy they are.
For example, according to
http://caloriecount.about.com, before toppings, a typical hamburger, depending on the lean meat/fat ratio, has somewhere between 150 to 213 calories. A Better Burger, one of the more popular vegetarian alternatives to hamburgers, has 390 calories before toppings.
Now, I will admit, in the case of foie gras and faux gras, the faux gras is somewhat healthier: foie gras has 250 calories while the same 2 oz serving of faux gras has 100 calories.
Admittedly, anyone who wants to eat foie gras probably isn't going to care about this anyway: people eat foie gras for the taste, not the calories. I just wanted to point out my rationale for why I don't always trust vegetarian alternatives to meat products. Were I to ever become a vegetarian again, I would want to cook dishes involving vegetable and fruits and avoid all these processed soy products.